Data from humans and animal models suggest that oxidative stress might play a part in the pathogenesis of hypertension. For example, patients and animals suffering from hypertension have been shown to increase reactive oxygen species (ROS) production and decrease antioxidant capacity. ROS, e.g., superoxide and hydrogen peroxide, have been shown to induce contraction and proliferation of vascular smooth muscle cells in vitro. The research described in this pilot project will examine the relationship between hypertension and oxidative stress in African-Americans. The goal of this study is to test the hypothesis that hypertension is associated with an increased oxidative stress, This project includes three specific aims: In specific aim 1, we will determine the relationship between hypertension and the concentration of plasma F2-isoprostane (an in vivo oxidative stress marker) and the production of blood hydrogen peroxide and superoxide. In specific aim 2, we will determine the relationship between hypertension and the activities of major antioxidant enzymes, including superoxide dismutases, catalase and glutathione peroxidases, in blood. In specific aim 3, we will determine the relationship between hypertension and the activities of ROS-generating enzymes, including xanthine oxidase and NADH/NADPH oxidase, in blood, if the hypothesis described above is correct, hypertensive patients will show a higher level of F2-isoprostanes, a higher production of ROS, higher activities of ROS-generating enzymes and/or lower activities of antioxidant enzymes than normotensive subjects. In this pilot project, we will focus on African-Americans because hypertension is more prevalent in African-Americans than that in Caucasians. However, no unifying hypothesis as to the genetic mechanisms responsible for the excess prevalence of hypertension among African-Americans has emerged. If results from this pilot project show that hypertension is associated with an increased oxidative stress, we will propose a study to compare the oxidative status of different populations, e.g., African-Americans and Caucasians with or without hypertension, to test if the high prevalence of hypertension in African-Americans is associated with a high level of oxidative stress.